1. A
Slides 1 to 110
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

2. Overview of Muscular System
Types of Muscle Tissue
Under voluntary control
Skeletal muscles
Attach to the skeleton
The muscular system
Under involuntary control
Cardiac muscle
Heart wall
Smooth muscle
Visceral organs
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

3. Overview of Muscular System
Skeletal muscles
Perform four functions
Produce movement of skeleton (“dynamic”)
Maintain posture, balance & body position (“static”)
Guard “entrances” (mouth) and “exits” (anus)
oral sphincter & anal sphincter
Maintain body temperature (ex: shivering)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

4. Anatomy of Skeletal Muscles
Gross (can see with “naked eye”) Anatomy
Connective tissue organization
Epimysium
Fibrous covering of whole muscle
Perimysium
Fibrous covering of fascicle
Endomysium
Fibrous covering of a single cell (a muscle fiber)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

5. Anatomy of Skeletal Muscles
The Organization of a Skeletal Muscle
Quiz on all of these!
Figure 7-1

6. Skeletal muscles attach to bones…
directly
by way of tendons (thick dense regular connective tissue “ropes”
indirectly
by way of aponeuroses (thin connective tissue (sheets”)

7. Stop Here!
Your first quiz will cover only the material on the first 5 slides that precede this one.

8. Anatomy of Skeletal Muscles
Microanatomy of a Muscle Fiber
Sarcolemma
Muscle cell membrane
Sarcoplasm
Muscle cell cytoplasm
Sarcoplasmic reticulum (SR)
Like smooth ER
Transverse tubules (T tubules)
Myofibrils (contraction organelle)
Sarcomeres
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

9. Anatomy of Skeletal Muscles
Sarcomere—Repeating structural unit of the myofibril
Components of a sarcomere
Myofilaments
Thin filaments (mostly actin)
Thick filaments (mostly myosin)
Z lines at each end
Anchor for thin filaments
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

10. Anatomy of Skeletal Muscles
The Organization of a Single Muscle Fiber
Figure 7-2(a)

11. Anatomy of Skeletal Muscles
The Organization of a
Single Muscle Fiber
Figure 7-2(b)

12. Anatomy of Skeletal Muscles
The Organization of a Single Muscle Fiber
PLAY
Anatomy of Skeletal Muscles
Figure 7-2(cde)

13. Anatomy of Skeletal Muscles
Changes in the Appearance of a Sarcomere During Contraction of a Skeletal Muscle Fiber
Figure 7-3 (1 of 2)

14. Anatomy of Skeletal Muscles
Changes in the Appearance of a Sarcomere During Contraction of a Skeletal Muscle Fiber
Figure 7-3 (2 of 2)

15. Control of Muscle Contraction
Steps in Neuromuscular Transmission
Motor neuron action potential
Acetylcholine release and binding
Action potential in sarcolemma
T tubule action potential
Calcium release from SR
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

16. Control of Muscle Contraction
The Neuromuscular Junction
Synaptic terminal
Acetylcholine release
Synaptic cleft
Motor end plate
Acetylcholine receptors
Acetylcholine binding
Acetylcholinesterase
Acetylcholine removal
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

17. Control of Muscle Contraction
The Structure and Function of the Neuromuscular Junction
Figure 7-4(a)

18. Figure 7-4(b-c) 1 of 5 Action potential Axon Synaptic terminal
Arrival of an action potential at the synaptic terminal
Axon
Arriving action potential
Synaptic terminal
Sarcolemma
Vesicles
ACh
Synaptic
cleft
AChE molecules
ACh
receptor
site
Muscle
fiber
Sarcolemma of
motor end plate
ACh binding at the motor and plate
Appearance of an action potential in the sarcolemma
Release of acetylcholine
Vesicles in the synaptic terminal fuse with the neuronal membrane and dump their contents into the synaptic cleft.
The binding of ACh to the receptors increases the membrane permeability to sodium ions. Sodium ions then rush into the cell.
An action potential spreads across the surface of the sarcolemma. While this occurs, AChE removes the ACh.
Action
potential
Na+
Na+
Na+
Figure 7-4(b-c)
1 of 5
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

19. Anatomy of Skeletal Muscles
The Contraction Process
Actin active sites and myosin cross-bridges interact
Thin filaments slide past thick filaments
Cross-bridges undergo a cycle of movement
Attach, pivot, detach, return
Troponin-tropomyosin control interaction
Prevent interaction at rest
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

20. Cross-bridge formation
Resting sarcomere
Active-site exposure
Cross-bridge formation
ADP
Myosin head
ADP +
Sarcoplasm P + P
Troponin
ADP + P
Ca2+
Ca2+
Ca2+
ADP
Active site
Ca2+
Tropomyosin
Actin +
ADP
ADP P P + P +
Myosin reactivation
Cross bridge detachment
Pivoting of myosin head
ADP
ATP
ADP + P + P
Ca2+
Ca2+
Ca2+
Ca2+
Ca2+
Ca2+
ADP P +
ATP
ADP + P
Figure 7-5
1 of 7
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

21. Control of Muscle Contraction
Summary of Contraction Process
Table 7-1

22. Control of Muscle Contraction
Key Note
Skeletal muscle fibers shorten as thin filaments interact with thick filaments and sliding occurs. The trigger for contraction is the calcium ions released by the SR when the muscle fiber is stimulated by its motor neuron. Contraction is an active process; relaxation and the return to resting length is entirely passive.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings